# std::wstring_convert<Codecvt,Elem,Wide_alloc,Byte_alloc>::wstring_convert

From cppreference.com
< cpp‎ | locale‎ | wstring convert

wstring_convert() : wstring_convert( new Codecvt ) {} | (1) |
explicit wstring_convert( Codecvt* pcvt ); | (2) |
wstring_convert( Codecvt* pcvt, state_type state ); | (3) |
explicit wstring_convert( const byte_string& byte_err, const wide_string& wide_err = wide_string() ); | (4) |
wstring_convert( const std::wstring_convert& ) = delete; | (5) | (since C++14)

Overload | Data members
--- | ---
`byte_err_string` | `wide_err_string` | `cvtptr` | `cvtstate` | `cvtcount`
(1) | default-initialized | new Codecvt | default-initialized | uninitialized
(2) | pcvt
(3) | state
(4) | byte_err | wide_err | new Codecvt | state_type()

2,3) If pcvt is a null pointer, the behavior is undefined.
5) The copy constructor is deleted, `wstring_convert` is not CopyConstructible.

### Parameters

pcvt | - | pointer to the conversion facet
state | - | initial value of the conversion shift state
byte_err | - | narrow string to display on errors
wide_err | - | wide string to display on errors

### Example

Run this code

    #include <codecvt>
    #include <locale>
    #include <utility>

    // utility wrapper to adapt locale-bound facets for wstring/wbuffer convert
    template<class Facet>
    struct deletable_facet : Facet
    {
        using Facet::Facet; // inherit constructors
        ~deletable_facet() {}
    };

    int main()
    {
        // UTF-16le / UCS4 conversion
        std::wstring_convert
            <std::codecvt_utf16<char32_t, 0x10ffff, std::little_endian>> u16to32;

        // UTF-8 / wide string conversion with custom messages
        std::wstring_convert<std::codecvt_utf8<wchar_t>> u8towide("Error!", L"Error!");

        // GB18030 / wide string conversion facet
        using F = deletable_facet<std::codecvt_byname<wchar_t, char, std::mbstate_t>>;
        std::wstring_convert<F> gbtowide(new F("zh_CN.gb18030"));
    }

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 2175 | C++11 | pcvt could be a null pointer | the behavior is undefined in this case
LWG 2176 | C++11 | constructors accepting single argument were implicit | made explicit
P0935R0 | C++11 | the default constructor was explicit | made implicit

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/locale/wstring_convert/wstring_convert&oldid=177289"